The present invention relates to an apparatus for measuring a dimension between a reference pattern and a pattern to be evaluated and a computer program for causing a computer to perform the measurement, and more particularly to a dimension measuring apparatus for measuring a dimension between corresponding points in a reference pattern and in a pattern to be evaluated and a computer program.
As the process rule for semiconductors evolves and a finer pattern is transcribed onto a wafer, an inspection utilizing design data becomes more useful for detection of a systematic defect caused by a design flaw of a mask or the like and for better dimension management. This is attributed to the increased importance of a measure against a systematic defect because, in addition that margins in setting of parameters for design and transfer of a mask are decreased so that a systematic defect tends to be generated, unlike a random defect, a systematic defect can be efficiently dealt with by identifying a cause of generation and taking a remedy.
A systematic defect, which is generated in the similar manner in all dies, cannot be detected by a conventional inspection in which dies are compared with each other, and it is desirable to be evaluated by an inspection by comparison to the design data or by dimension management using the design data. In addition, as for dimension measurement, dimension measurement of only one-dimensional features is getting insufficient and an increasing need has arisen for evaluation of two-dimensional shapes.
Against such a background, as examples of inspection technologies utilizing design data, there are those disclosed in JP-A-2006-275952 and JP-A-2004-185019.
In JP-A-2006-275952, disclosed is a technology in which a contour of a reference pattern and a contour of an inspection pattern are compared with each other and inspected using distance transform images. More specifically, a distance transform image generated from a contour of a reference pattern is used to obtain a distance from each of the points on a contour of an inspection pattern to the nearest point on the contour of the reference pattern and, using the obtained distance, the inspection pattern is evaluated.
In JP-A-2004-185019, disclosed is a technology in which, by introducing a concept of an “edge” that is defined on a pixel basis and has a start point with sub-pixel accuracy and a direction of a contour at the pixel, a correspondence between a point on a contour of a reference pattern and a point on a contour of an inspection pattern is obtained while not only a distance but also a direction is considered so that the contour of the reference pattern and the contour of the inspection pattern are compared with each other and inspected using the obtained correspondence.